Our Brave Instrumentality
Woohoo! Mars lander made it down safely! For whatever reason, I have a strong tendency to anthropomorphize autonomous space equipment. In my mind, it's a brave little device, risking itself to gather information for Man, more Instrumentality than instrument.
That is an astonishing amount of dirt stuck to the lens protector, and some of it pretty big chunks too. You generally associate that with wet dirt. That's presumably what got kicked up by the engines at landing. Those are hydrazine monopropellant engines , with the fuel decomposing over a catalytic bed (rhodium? platinum?) instead of burning with an oxidizer, so there's no water in the exhaust - just nitrogen and ammonia.
One supposes that if the Viking science team's theory about iron peroxide existing at the surface of the Martian soil is correct (and I have honestly always considered it unlikely), then the hot ammonia is probably burning off to form water. The exhaust would have to be hot enough to start the reaction, yet not so hot that all the water gasses away. I can't find any data on the exhaust temperature of those thrusters, and I'm disinclined to try to do the enthalpic calculations myself, as someone will undoubtedly think all this out in far more detail than I, and post the numbers online in a day or two.
So, for the moment, the sticky dirt remains a fun anomaly that invites speculation.
*****
And, CubeSats on their way to deep space!
Edit: And, as someone pointed out in conversation elsewhere, if the lens protector dome is plastic, then dry dirt heated and kicked up by the exhaust might stick like that also.
Original posted at https://rain-gryphon.dreamwidth.org/61934.html
That is an astonishing amount of dirt stuck to the lens protector, and some of it pretty big chunks too. You generally associate that with wet dirt. That's presumably what got kicked up by the engines at landing. Those are hydrazine monopropellant engines , with the fuel decomposing over a catalytic bed (rhodium? platinum?) instead of burning with an oxidizer, so there's no water in the exhaust - just nitrogen and ammonia.
One supposes that if the Viking science team's theory about iron peroxide existing at the surface of the Martian soil is correct (and I have honestly always considered it unlikely), then the hot ammonia is probably burning off to form water. The exhaust would have to be hot enough to start the reaction, yet not so hot that all the water gasses away. I can't find any data on the exhaust temperature of those thrusters, and I'm disinclined to try to do the enthalpic calculations myself, as someone will undoubtedly think all this out in far more detail than I, and post the numbers online in a day or two.
So, for the moment, the sticky dirt remains a fun anomaly that invites speculation.
*****
And, CubeSats on their way to deep space!
Edit: And, as someone pointed out in conversation elsewhere, if the lens protector dome is plastic, then dry dirt heated and kicked up by the exhaust might stick like that also.
Original posted at https://rain-gryphon.dreamwidth.org/61934.html